topic Re: colorizing a black and white Imagery Layer in ArcGIS JavaScript Maps SDK Questions

colorizing a black and white Imagery Layer

roch — Mon, 01 Mar 2021 18:53:32 GMT

Hello !

I am using the terrain elevation layer wich is black and white but I'd like to give it some color for more user friendly look.

For instance black to blue grey to green and white to red or more steps .. is there a built in library for this ?

thank you

Re: colorizing a black and white Imagery Layer

JohnGrayson — Mon, 01 Mar 2021 19:16:40 GMT

Can you please share a simple CodePen showing us what you've tried so far?

Re: colorizing a black and white Imagery Layer

johnbrosowsky — Mon, 01 Mar 2021 19:57:59 GMT

use blend modes: Intro to layer blending | ArcGIS API for JavaScript

Re: colorizing a black and white Imagery Layer

roch — Mon, 01 Mar 2021 22:28:32 GMT

@JohnGrayson well right now I'm gathering informations on how to do this so I have nothing to show. I just made a map with markers yet ...

@JohnGrayson thank you for your answer but , as I understand how blending work from photo editing , It could be part of the answer If I could blend only specific parts of the grayscale one at a time(black to red, gray to green and white to red), wich would also seem very coslty.

I want to end up with something like this

Re: colorizing a black and white Imagery Layer

johnbrosowsky — Mon, 01 Mar 2021 22:30:41 GMT

example where you can define a color ramp to apply: https://developers.arcgis.com/javascript/latest/sample-code/sandbox/index.html?sample=layers-imagery-renderer

Re: colorizing a black and white Imagery Layer

calimucho — Tue, 02 Mar 2021 10:16:33 GMT

wow ! I did bot now about RasterShadedReliefRenderers, it's really cool thanks 🙂 I think indeed the color ramp is what I was looking for ! thanks a lot

last question though : colorrange remaps the grayscale of the whole terrain map to the given colors, is it possible to make the color range refine to a zoomed-in region min and max altitude ?

Re: colorizing a black and white Imagery Layer

calimucho — Tue, 02 Mar 2021 10:51:37 GMT

@johnbrosowsky could I not use RasterColorMapRenderer then ? I made this but does not seem to work ... https://codepen.io/ebkgne/pen/mdOLLep

Re: colorizing a black and white Imagery Layer

JohnGrayson — Tue, 02 Mar 2021 21:26:14 GMT

The doc says "The RasterColormapRenderer is only available if a color map is present in an ImageryLayer or ImageryTileLayer." but the service you are trying to use doesn't have a color map defined. Instead, you can use a ClassBreaksRenderer to achieve what you'd like; check out this CodePen: https://codepen.io/john-grayson/pen/RwoJbPq

Re: colorizing a black and white Imagery Layer

calimucho — Wed, 03 Mar 2021 10:43:34 GMT

@JohnGrayson hey ! well I did not get how classBreakRenerer worked before, I'm learnig a lot on this thread thanks ! Do you think it'd be very costly / overkill to put let say a 100 ClassBreakInfo for a gradient like colorizing ? and alternative question, with the RasterShadedReliefRenderers, would it be less costly (still quite overkill) to play with duplicating first and last values in the MultipartColorRamp to achieve a similar render. hope I made myself clear ... thx !

Re: colorizing a black and white Imagery Layer

calimucho — Wed, 03 Mar 2021 14:32:14 GMT

well I kinda got where I want, here is the codepen https://codepen.io/ebkgne/pen/xxRzrPN , I went with the first solution, my only question then is why it's not updating ... i'm doing exactly like @johnbrosowsky example, cloning renderer, editing, re assigning on event trigger ...

Re: colorizing a black and white Imagery Layer

JohnGrayson — Wed, 03 Mar 2021 16:01:03 GMT

Check out all of the available renderers and yes, maybe the RasterColormapRenderer or RasterShadedReliefRenderer might be better fits for what you need.

Re: colorizing a black and white Imagery Layer

calimucho — Fri, 28 Jan 2022 14:59:26 GMT

ok so .... couple month later ^^

on the last codepen, about not updating, problem was, I was not using ArcGIS event system ..., I updated the sources. but it's quite a slow solution,

So I came up with way faster solution using RasterShadedReliefRenderer colorRamp (like previously suggested actually ^^) , see here : https://codepen.io/ebkgne/pen/eYeNPyw